Babies' bodies make the lactase enzyme so they can digest milk, including breast milk.

Babies born too early (premature) sometimes have lactose intolerance.

Children who were born at full term often do not show signs of the problem before they are 3 years old.

Lactose intolerance is very common in adults. It is rarely dangerous. Around 30 million American adults have some degree of lactose intolerance by age 20.

In Caucasians, lactose intolerance often develops in children older than age 5.

In African Americans, the problem can occur as early as age 2.

The condition is very common among adults with Asian, African, or Native American heritage.

It is less common in people of northern or western European background, but still may occur.

An illness that involves or injury your small intestine may cause less of the lactase enzyme to be made. Treatment of these illnesses may improve the symptoms of lactose intolerance. These may include:

Surgery of the small intestine

Infections in the small intestine (This is most often seen in children)

Diseases that damage the small intestines, such as celiac sprue or Crohn's disease

Babies may be born with a genetic defect and are not able to make any of the lactase enzyme.

Cutting down your intake of milk products that contain lactose from your diet most often eases symptoms. Also look at food labels for hidden sources of lactose in non-milk products (even some beers) and avoid these.

Most people with low lactase levels can drink up to one-half cup of milk at one time (2 to 4 ounces) without having symptoms. Larger servings (more than 8 oz.) may cause problems for people with the deficiency.

Milk products that may be easier to digest include:

Buttermilk and cheeses (which contain less lactose than milk)

Fermented milk products, such as yogurt

Goat's milk

Ice cream, milkshakes, and aged or hard cheeses

Lactose-free milk and milk products

Lactase-treated cow's milk for older children and adults

Soy formulas for infants younger than 2 years

Soy or rice milk for toddlers

You can add lactase enzymes to regular milk. You can also take these enzymes as capsules or chewable tablets. There are also many lactose-free dairy products available.

Not having milk in your diet can lead to a shortage of calcium, vitamin D, riboflavin, and protein. You need 1,000 to 1,500 mg of calcium each day depending on your age and gender. Some things you can do to get more calcium in your diet are:

Take calcium supplements with Vitamin D. Talk to your health provider about which ones to choose.

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